The insufficient supply of photosynthates source of grains is considered to be one of the causes of chalkiness, a key factor in determining rice quality. In China, Zhaoqing University's Yonghai Liu studied the enzyme L-galactono-1, 4-lactone dehydrogenase (L-GalLDH, EC1.3.2.3), the catalyst for the final step in the synthesis of ascorbic acid (Asc) and its effect on grain chalkiness.

Researchers found that the L-GalLDH-overexpressing transgenic rice, GO-2, contains a higher Asc content in leaves than wild-type plants and exhibits reduced grain chalkiness. Further analysis showed that the enhanced level of Asc resulted in a significantly higher ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco) protein level in GO-2 which increased the photosynthetic rate.

These results reveal that the enhanced level of Asc affects the chalkiness in GO-2 grains by maintaining photosynthetic function in leaves at key developmental stages related to grain filling.

For more information, read the full article on Science Direct. The Crop Journal

Available online 23 February 2015

http://www.sciencedirect.com/science/article/pii/S221451411500015X

Fig. 1. Grain chalkiness and starch granule morphology comparison between GO-2 and WT.

(A) Chalkiness degree of GO-2 and WT grains.

(B) Polished grain of WT (left) and GO-2 (right).

(C) Scanning electron microscopy images of transverse sections of WT (left) and GO-2 (right) grains. Bars, 10 μm.

Data in (A) are presented as means ± SE of at least 50 replicates, and those that were significantly different from one another according to Fisher’s protected LSD test are indicated by different letters (P < 0.05).